diff --git a/comms.c b/comms.c
index 614d0dd..67f2410 100644
--- a/comms.c
+++ b/comms.c
@@ -13,7 +13,7 @@ _strobe_state_size()
 }
 
 void
-comms_init(struct comms_state *cs, process_msgfunc_t pmf)
+comms_init(struct comms_state *cs, process_msgfunc_t pmf, struct pktbuf *shared)
 {
 
 	*cs = (struct comms_state){
@@ -23,9 +23,11 @@ comms_init(struct comms_state *cs, process_msgfunc_t pmf)
 
 	strobe_init(&cs->cs_start, domain, sizeof domain - 1);
 
+	if (shared != NULL)
+		strobe_key(&cs->cs_start, SYM_KEY, shared->pkt, shared->pktlen);
+
 	/* copy starting state over to initial state */
 	cs->cs_state = cs->cs_start;
-
 }
 
 #define CONFIRMED_STR_BASE	"confirmed"
diff --git a/comms.h b/comms.h
index e53062d..b9e44fb 100644
--- a/comms.h
+++ b/comms.h
@@ -27,5 +27,5 @@ struct comms_state {
 
 size_t _strobe_state_size();
 
-void comms_init(struct comms_state *, process_msgfunc_t);
+void comms_init(struct comms_state *, process_msgfunc_t, struct pktbuf *);
 void comms_process(struct comms_state *, struct pktbuf, struct pktbuf *);
diff --git a/lora.py b/lora.py
index 2a2e045..a05eadd 100644
--- a/lora.py
+++ b/lora.py
@@ -22,9 +22,11 @@ CMD_RUNFOR = 3		# arg: (chan, length): turns on chan for length seconds
 class LORANode(object):
 	'''Implement a LORANode initiator.'''
 
-	def __init__(self, syncdatagram):
+	def __init__(self, syncdatagram, shared=None):
 		self.sd = syncdatagram
 		self.st = Strobe(domain, F=KeccakF(800))
+		if shared is not None:
+			self.st.key(shared)
 
 	async def start(self):
 		msg = self.st.send_enc(os.urandom(16) + b'reqreset') + \
@@ -177,10 +179,14 @@ def timeout(timeout):
 class TestLORANode(unittest.IsolatedAsyncioTestCase):
 	@timeout(2)
 	async def test_lora(self):
+		shared_key = os.urandom(32)
+
 		class TestSD(MockSyncDatagram):
 			async def runner(self):
 				l = Strobe(domain, F=KeccakF(800))
 
+				l.key(shared_key)
+
 				# start handshake
 				r = await self.get()
 
@@ -234,7 +240,7 @@ class TestLORANode(unittest.IsolatedAsyncioTestCase):
 				    l.send_mac(8))
 
 		tsd = TestSD()
-		l = LORANode(tsd)
+		l = LORANode(tsd, shared=shared_key)
 
 		await l.start()
 
@@ -308,12 +314,15 @@ class TestLORANode(unittest.IsolatedAsyncioTestCase):
 					# pass the reply back
 					await self.put(outbytes[:outbuf.pktlen])
 
+		# Generate shared key
+		shared_key = os.urandom(32)
+
 		# Initialize everything
-		lora_comms.comms_init(commstate, cb)
+		lora_comms.comms_init(commstate, cb, make_pktbuf(shared_key))
 
 		# Create test fixture
 		tsd = CCodeSD()
-		l = LORANode(tsd)
+		l = LORANode(tsd, shared=shared_key)
 
 		# Send various messages
 		await l.start()
diff --git a/lora_comms.py b/lora_comms.py
index b2830b6..605591f 100644
--- a/lora_comms.py
+++ b/lora_comms.py
@@ -49,7 +49,7 @@ class CommsState(Structure):
 	]
 
 for func, ret, args in [
-    ('comms_init', None, (POINTER(CommsState), process_msgfunc_t)),
+    ('comms_init', None, (POINTER(CommsState), process_msgfunc_t, POINTER(PktBuf))),
     ('comms_process', None, (POINTER(CommsState), PktBuf, POINTER(PktBuf))),
     ('strobe_seed_prng', None, (POINTER(c_uint8), c_ssize_t)),
     ]: